Internal thread gage



1s, 194s. J1. F. ANDERS 2,434,535

INTERNAL TREAD GAGE Filed Sept. 29, 1944 qraql- I4 40 I N VEN TOR. J'Obn I''n 02ers Patented Jan. 13, 1948 JNVEEE STATES FA'ENT QFFICE.

INTERNAL THREAD GAGE John F. Anders, Kitchawan, N. Y.

Application September 29, 1944, Serial No. 556,362

(C1. .sa-17e) 1 Claim.

This invention relates to thread gages.

The object of the invention is to provide a quick-acting, direct-reading, uniform pressure, internal thread gage having interchangeable parts for use in threaded holes of diiferent diameter and shape.

A preferred embodiment of the invention is illustrated in the accompanying drawing in which Fig. l is a plan view of the device;

Fig. 2 is a longitudinal section thereof on the line 2-2 of Fig. 1;

Fig. 3 is a front or head-on View of the head of the device;

Fig. 4 is a transverse section on the line ,4--4 of Fig. 1;

Fig. 5 is a plan view of the graduated scale plate; and

Fig. 6 is a plan view, partly broken away, of the actuating shaft of the device.

The thread gage herein claimed has a twopiece housing construction, the head member Ill and the handle member 2i). They are joined end to end by means of screws I I.

The head member comprises a tubular portion I2 having three radial arms |`3 integral therewith, an end plate I4 which has three corresponding arms I5 and three side plates I 6 which are sandwiched in between said arms I3 and I5 and to which said arms are afxed.

Toothed segments I1 and slotted segment I8 are carried in the spaces formed between each radial arm I3 and its corresponding end plate arm I5 and between the side plates I6 which said arms adjoin. Segments I 'I are fixed in said spaces by means of screws I9. Segment IB is radially movable in its space, being slidably Xed therein by means of bolt 9 which passes through its slot 8. A compression spring 'I is carried within said slot, being braced against bolt 9 and tending, thereby, to urge segment I3 inwardly.

The handle member 29 comprises a tubular member having a rectangular window 2 I formed centrally thereof, said window being flanked by a pair of diametrically opposite slots 22 which are formed longitudinally of said member. graduated scale '23 having slotted ends 24 is adjustably fixed by means of screws 25, to said handle member, longitudinally thereof, adjacent to, and paralleling said window.

A transparent sheet 25 covers said window and said scale, being raised slightly above the latter. An escutcheon 2l is screwed to the handle member by means of screws 28, holding said transparent sheet in place. The handle member is closed at its free or rear end by means of axially apertured screw cap 29 whose aperture has an enlarged, threaded portion 30.

fSlidably disposed in said handle and head members is a shaft 40 whose forward end Vhas a downwardly sloping. flattened portion 4I which serves as an inclined plane, andV whose rear end 42 is of hollow construction and of reduced outer circumference. A shoulder 43 is formed at the juncture between the main body of the shaft and the reduced rear end.

Transversely fixed in said shaft is a linger grip 44 which, when the shaft is disposed in said handle and head members, protrudes through slots` 22. Afxed to said shaft adjacent said nger grip, and at right angles thereto, is an indicator arm i5 having an indicating finger which occupies the space between the scale 23 audits transparent covering 26. The finger is adapted to ride o'ver, and lengthwise of, the scale, when the shaft is moved longitudinally of the head and handle members.

A compression spring 50, carried by the reduced rear end of the shaft and braced between screw cap 25 and shoulder 43, urges said shaft forward. Acting against the pressure of said spring is an air check valve 5I. Said valve includes an axially apertured shaft 52 whose forward portion is disposed in the hollow rear portion 42 of the main shaft 40 and whose rear portion is enlarged and threaded to t into the enlarged, threaded cap screw aperture 3D. The axial hole or boring 53 in shaft 52 has an enlarged rear portion which accommodates a ball 54, an axially apertured, internal plug or nut 55 and a small compression spring 56 braced between said ball and said plug.

A lever of the third class 6I] is pivoted to the head member I0, longitudinally thereof. It carries a .centrally disposed, transverse roller 6I whichA is engaged by the flattened sloping portion 4I of the main shaft. Its free end 62 is ball or roller shaped, and is adapted to engage the under surface of radially movable segment i3 against the pressure of spring 'I.

The device may be used as follows:

The nger rip is pulled back, thereby causing rearward movement of shaft 4B against the action of spring 50. This has the effect of partially disengaging the lever 60 and of permitting segment IB to move inwardly in response to the thrust of spring l. A further effect is the evacuation of much of the air in the hollow end 42 of the shaft, through boring 53 and the aperture in plug 55. It also has the effect of drawing air :into the tubular portion I2 of the head member Vhousingjtwo iixed and through the clearances between the segments and the plates which surround them.

The device is now ready for insertion into the threaded aperture sought to be measured. The finger grip is released, thereby enabling the shaft 40 to move forward in respose to the action of spring 5D. Sudden forward movement is blocked, however, by the cushion of air in front of the shaft, and by the partial vacuum behind it. Only slowly isithe air gcushlon evacuated, andtheva uum lleci.` Air passes into the hollow portion d2v past ball 54 which spring 56 holds against the opening of boring 53.

The result is that when shaft 40 is permitted.

to move forward and to engage leverwhich' in turn engages segment I8 and pushes theafmef outwardly against the tension of *springY 1, there is always uniform pressure of 'the shaft -uponthe lever, and of the lever upon the segment.

The function of the slots in the scale 23 is to provide for adjustment Athereof ,relative to, the position of' @effacements-,and also to cgmpensate forwear ofthepa sf n internal screw lthread gage comprising: a f I i one radially -mfoi'fable'[segf` ments radially disposed therin'fthe freee'nds of said segments being 'prov'id'efdf with Ate'eth'f4 which are adapted to msh'with A'internalscrewthz'eads, acornp'rssio'n s "pri'rg`V 'femb'er 'engagirr'igsaid ra'- rlially` movable segmentaid furgingsaid segment tovpmy'e mwai-diy, a'ibngipgdinauy'moyableishaft longitudinally'earried in said -rhou'singfandhaving a gently tapered reduced forward end, a longitudinally extending arm pivoted at one end to said housing, its free opposite end engaging the inner end of said radially movable segment, said arm being provided intermediate its two ends with a transversely disposed roller which engages the tapered forward end of the shaft, a second compression spring member engaging said shaft and urging it forwardly whereby outward radial movement of the movable segment' is eilected against the laction lof the first springmember, a finger grip on the shaft whereby it may be moved rearwardly against the action of the second spring memher.,thereby effecting an inward radial movement of said movab`e segment by releasing it to theacltionpf the rst spring member, an air check valve cushioningthe forward movement of the shaft eiected by theV action of the second spring member, a longitudinally extending graduated scale adjustably xed on the housing and an indicator thereforfd on the shaft- Annees.

REFEENQeSfCl-.TED The following references are .of ,record in the file -Qf this-patent:

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